Arcade Collecting > Miscellaneous Arcade Talk

Reproduction Atari Volcano Switch Voltage

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Drakkorcia:
Scott,

I found some dupont wires but they are too short to reach my i-pac and its headers so it will be better to use my 12v chain. Instead, I'm opting for a 1/4 resistor pack on Amazon with 60 levels of resistance. Would this be a good pack, and which ohm level would you use for that 12v? There is also a YouTube video of someone putting these into his A1UP by tapping into his 12v with a 220 ohm resistor without issue. If you give the okay, I'll get the pack.

https://www.amazon.com/gp/product/B08PF3HNMD/ref=ewc_pr_img_1?smid=A14FP9XIRL6C1F&psc=1

PL1:

--- Quote from: Drakkorcia on January 24, 2022, 07:52:42 pm ---It would help if there was actually some documentation on these repro's. Maybe the LED on it can handle 5 volts?

--- End quote ---
Agreed, but we can (somewhat) reverse engineer the specs with this simple test.   :cheers:

Best way to tell for sure is to use your multimeter in series to test how many miliAmps are flowing through the circuit below  while the LED is forward biased/lit.
- Use one LED and one resistor as shown so there's no fancy serial/parallel circuit math and it's also a best practice to use a separate resistor for each LED and in this case it will keep you from exceeding the wattage and burning up a 1/4 W resistor like the ones you're getting.   :scared
- With a 2v LED and a 680 ohm resistor, you should get something close to 15 mA.
- With a 2v LED and a 510 ohm resistor, you should get something close to 20 mA.

12v ---- current limiting resistor ---- + LED - ---- red lead--multimeter--black lead ---- ground

If your readings are much lower (i.e. 2 or 3 mA), there's likely a current limiting resistor hidden inside the volcano button assembly.  Post the results of both tests and I'll try to (somewhat) reverse engineer it.


--- Quote from: Drakkorcia on January 24, 2022, 08:57:15 pm ---I'm opting for a 1/4 resistor pack on Amazon with 60 levels of resistance. Would this be a good pack, and which ohm level would you use for that 12v?

--- End quote ---
That would be a fine assortment.   :cheers:
- The 680 ohm should be extremely safe. (15mA)
- The 560 ohm should be very safe.
- The 510 ohm should be safe. (20mA)


--- Quote from: Drakkorcia on January 24, 2022, 08:57:15 pm ---There is also a YouTube video of someone putting these into his A1UP by tapping into his 12v with a 220 ohm resistor without issue.

--- End quote ---
I'll take my 40+ years of experience working and playing to component level with electronics over the word of some YouTube rando that managed to get the LEDs to last long enough to shoot a video.
- I don't want to pick on him, but it's clear that if he is knowledgable about electronics he isn't clearly conveying that info and isn't following best practices.  Caveat emptor.

The measurements from the inline amperage test mentioned above will provide valuable insight into what you're actually dealing with.

Unless there is a current limiting resistor hidden inside the volcano button or the LED specs are way outside the usual range for red LEDs, the video results do not make sense.

There's probably some unidentified variable in the equation because it's called Ohm's Law, not Ohm's Suggestion.   :lol


Scott

Drakkorcia:
Thank you sir. The youtuber was just to point out someone put too small a resistor on and was probably lucky. I wanted to confirm with you. Obviously I trust you and your experience which is why I opted for the pack so there would be more powerful resisters to choose from. These repro's aren't like some 50cent lamp you can experiment with and be wrong; they cost $15.95 and are currently unavailable. So I want to get it right.

That's why I made this thread because I was getting ready to plug it into a 12V chain until I decided to ask someone who knows what they're doing. Good thing I did. On Amazon they like to sell resistors in 100pcs packs which would be a waste if I only need two so I figured buy an assortment so I can have different sizes down the road. Mostly, I wanted to make sure the 1/4 watt was correct; all that stuff is a bit over my head for now but I appreciate your help and will be able to learn from this thread. Thanks again.

PL1:
Glad to assist.   :cheers:

Once your resistors come in, we'll do the testing, get you safely up and running, and maybe learn/confirm some details about these LED switches.   ;D


Scott

Zebidee:
There was a Facebook thread recently on volcano buttons and I mentioned the need to use a resistor with them, but somebody else commented that they now have a resistor built-in. Not a great authority, but there you are.

One thing we do know is that you can add another resistor, or use a higher value resistor, without breaking anything. The LED will probably still light, but with slightly lower brightness. Worst that can happen is the LED won't light.




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